The nature of kindness is explored—its relationship to love and generosity, as well as the characteristics that distinguish it from pity. Kindness is defined as an intentional and selfless kind of gentle love that involves concentrating on the needs of another person. It is the opposite of cruelty and neglect, which ignore the needs of others and focus only on the self. Joy is likewise examined, and Koenig notes how it differs from the emotions of happiness and satisfaction. Its roots are shown to be in human experiences and actions.

Stories from everyday life as well as the acts of well-known people illustrate how kindness is expressed. They also show the effects of kindness on the person who is being kind and the recipient of the kindness. While, to date, there is little formal research on kindness, there are studies on the positive impact of values that are related to it, such as forgiveness, altruistic love, and acts of volunteering and compassion. It is likely, Koenig speculates, that kindness will be found to have a positive effect on mental health and even physical health.

This book includes guidance as well as information and inspiration. There are practical recommendations on how to perform acts of kindness in personal lives and at work, toward friends, colleagues, and family members—even with one's enemies. Suggestions are also offered on ways to encourage others to be kind so they, too, can experience the joy that results.

Kindness and Joy shows that kindness is a virtue that carries a double blessing: it transforms both the life of the receiver and of the giver.